Apparatus for unloading compressors



Oct.

1927 w. H. CALLAN- APPARATUS FOR UNLOADING COMPRESSORS 2 Sheets-Shoot 1 Filed Sept. 1, 1923 IV VE N TOR Wl/liam H Cal/an BYAA ATTORNEY Oct." 18, 1927,

w H. CALLAN APPARL TUS FOR UNLOADING COMPRESSORS Filed Sept 1,. 1925-' 2 sheets-sum i 2 //V YEW T 0R 7 Will/0m H E a/lab A BYAQ'. ATmR/VEY,

Patented Oct. 18 1b27.

UNITED STATES 1,645,798 PATENT OFFICE.

WILLIAM H. CALLAN, F CLEVELAND, OHIO, ASSIGNOR T0 CHICAGO PNEUMATIC TOOL COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

arrann'ros ron UNLOADING comrans'sons.

Application flled'september 1, 1923. Serial No. 660,654.

This invention relates to air and gas compressors andpumps and to apparatus for unloading the same adapted to be controlled automatically in response to variations 1n 5 receiver pressure.- More particularly it concerns apparatus of this character in which valves are positively held open or closed by fluid pressure released in limited amount by a controller or actuator device responsive to predetermined receiver pressure.

Her'etofore it has been customary to arrange the unloading valves to be operated "bf-the fluid pressure released directly thereto by, the actuator. Under favorable circum- 16 stances such operation is satisfactory even when a plurality of unloading valves are controlled by'one actuator, as in large com pressors. .However in practice 'more'or less leakage develops in the pipe lines due to the 2 vibration of the machine and-to other causes,

resulting frequently in so reducing the pressure supplied to the. unloading valves by the actuator that relative movement ofthe parts occurs as the compressor piston continues to reciprocate. Rapid wear follows with still greater leakage until complete fallure of the unloading valves to operate results. It is not unusual also for irregular action of the unloading valves to arise from the presence of a particle'of grit or of other foreign matter including water or oil, by reason of the restricted amount of fluid pressureadmitted to thevalves by the actuator.

Among the objects of the invention are to efiect more reliableoperation of the unloading valves, to provide means for this purpose simple in form, cheap to manufacture and easy to install upon either old or new compressors, and in general to overcome thc de- 40 fects of previous apparatus with aminimum of expense and trouble. The invention comprises the interposition between the actuator device and the unload: ing valve or valves of an auxiliary valve di rectly controlled'by the actuator and in turn adapted to subject the unloading valves'to" substantially full line 'or receiver pressure thereby to effect prompt andpositlve operation thereof in varying the load of the compressor.

in order to illustrate the invention one concrete embodiment thereof is shown in the accompanying drawings in-which: Figure 1 is a view partly inelevation and apparatus disclosed in Fig. 1 being indicated partly in section, illustrating an installation of the-invention; and

Flg. 2 is a sectional viewon an enlarged. scale of the invention, associated parts of the in dot and dash outline.

In the embodiment of the invention chosen for the purpose of illustration and illustrated in Fig.1, actuators A and Af responsiveto predetermined receiver pressure, control the operationbfunleading valve assemblies B and B upon the right and left ends respectively of the double actin compressor cylinder C, which is provide with a piston D reciprocated by any suitable source of power (not shown). Any number of actuators A and A may be used to control the unloadin valve assemblies B and B to eflect unloa ing of the compressoncylinder in any desired number of steps. While any desired and suitable 'type of actuator may be used, that illustrated in the drawings is; disclosed and claimedin Patent No. 1,224,27 2 of May 1st, 1917, issued to myself and G. J. McFadden. Briefly this actuator or differential unloader A comprises a casing having a chamber aconnected to the compressor receiver (not,shown)-by a pipe a and having a second chamber a normally open to atmosphere by ports a. A valve a controls communication between chambers a and a and normally closes chamber a through the action of'a plunger (1 which maintains a yielding pressure upon the valve a due to the thrust of a spring a", the tension of which may be varied by an adjusting screw a' provided with a lock nut a. When the receiver pressure exceedsthe pressure of spring a, valve (1 is forced downwardly cutting of? communication between chamber d and atmosphere and admitting to chambera through restricted ports a pres: sure in limited amount to actuate the unloadingyalves. In practice it has been found necessary to make ports a? few in number and very-small in order that the air pressure against valve a may not be reduced to'such an extent on unseating of the valve as to ause" fluttering.

The unloading valves-may, likewise be of an suitable or desired type and arranged to ance pockets integral with the compressor cylinder or separate therefrom. The type of unloading valve disclosed in the drawing is that well-known in the art under the name of Simplate valve and is shown and described in -my prior- Patent No. 1,275,848 issued August 13, 1918. In brief this valve comprises annular plates -b normally maintained in contact with an apertured valve seat I) by coil or volute springs mounted in a valve cage or keeper these parts being secured to a stud 'b 'held in place in a proper manner by the valve cover 6 The valve lifter b is slidable on -valve stud I) being maintained in raised position by springb. To unload the compressor the valve lifter is forced against the v. for the purposeof subjecting the latter to valve plates bto holdthe same spaced from seat I) by a piston b movably by fluid pres sure admitted through a pipe 5 In order to overcomefailures and irregularities in operation of the unloading valves through insuflicient pressure admitted by the restricted ports a of the actuator valves, which pressure is often still further diminished by leakage in the pipe connection or .nullified by grit, oil and water carried to the movable parts bythe motive fluid itself, auxiliary valves E andE, comprising the present invention, are interposed between the actuator valves A and A apd the unloading valves B and B controlled thereby full line. or receiver pressure on operation of the actuator valves as heretofore described. Each auxiliary valve com risesa casing 3 having an axial bore theret irou'gh,

enlarged at various points to form chambers.

A iston 5, which may be hollowed out as indicated to reduce its weight, is mounted for axial movement at one end of casing 3 in an enlargement 4 of the axial bore. The end of the casing3 is closed in an air-tight manner by a suitable cover 6 having a pipe 7 communicating with chamber a of the associated actuator valve whereby on admis sion of receiver pressure to chamber a? through restricted ports a piston 5 will be moved downwardly in an obvious manner. Piston 5 carries an axial extension or valve stem 8 extending through thebore of the casing 3, the lower end of which is subjected to the yielding pressure of a coil spring 9 bearing against a screw plug 10,.

whereby the piston 5 is normally maintained in elevated position as shown inFig. 1. The lower end of enlarged chamber 4'beneath the piston 5v forms a chamber 11 communicating with atmosphere through a passage 12. Below chamber 11 and communicating therewith by an angularly disposed passage 13 is a second chamber 14 with which pipe 6 of the unloader valve connects. Below chamber 14 is a third chamber 15 constantly in communication with the compressor rebeing so positioned on stem 8 that they are alternatively in contact with theiri respective cooperating seats.

l/Vhen the parts are in normal position, as disclosed in Fig. 1 with pistono near .the top of its chamber, communication between chambers 15 and 14 is cut off, but established.

between chambers 14 and 11 by passage 13.

Consequently the unloading valveilsvented to atmosphere and is in inoperative P05113101! for unloading the cylinder. When the receiver pressure builds'up sufliciently to cause operation of the actuator valve or differential unloader the parts take 1% position shown in Fig. 2, in which fluid pressure admitted to chamber 4 forces-piston 5 downwardly seating valve 17, thus cutting off chamber 14 from atmosphere,-and at the same time unseating valve ,19 whereby the full receiver pressure from pipe '16 passes through chamber 15 around reduced neck 8f to chamber 14 through pipe b to piston 5".

of the unloading valve which in turnj fores valve lifter b to hold valves 6 off their seats so. long as the receiver pressure overcomes the spring a of the actuator valve. When the receiver pressure is reducedand actuator valve a again closes chamber a, the pressure above piston 5 of the auxiliary valve is vented through pipe 7, chamber a and ports a, whereupon valve stem 8 and piston 5' are forced upwardly by'spring 9 thus closing valve 19iand openin valve 1i, whereby the chamber of the un oading piston b is open to atmosphere through pipe b ,'chamber 14, passage 13, chamber '11 and vent 12, thus rendering the unloading valve inoperative. i

From the above it will be apparent thatthe auxiliary unloader valve formingthe, present invention is a separate and distinct unit adapted to work "in conjunction with and auxiliary to regular or standard unloading mechanism, that its installation requires and involves no change whatever either in structure or in functioning of the original actuator or unloader or of the unloading valves, that while unload'in mechanism can operate with or without t e invention its use as an auxiliary to such mechanism overcomes all irregularities and failures in the operation of the unloading valves due to insuflicient volume and pressure, that the device of the present invention is entirely automatic in operation, and that in additidn to ity as to permit its production on a lowcost basis. I v 4 Having described my invention whatI claim as new is: p

As a new article of manufacture, an auxiliary valve for use in compressor control systems arid adapted to be inserted as a unit between the actuator or difierential-unloader valve and the unloading valves .toact as a relay under control of said actua'torfor admitting the compressed fluid in volume and at full pressure to the unloading valves comrising a casing having a series of chambers in axial alignment, a. piston in the upper chamber, a stem extending through the control chamber and cutting off communication axially between said control chamber and said upper chamber, a valve disposedv in said lower 0 to the unloadin amber to control communication be tween the lower chamber and the control chamber, a single spring beneath said valve for normally maintaining the-same in closed yieldingly to maintain'said piston spaced from t e lower end of said upper chamber, said u per chamber below said piston being vented to atmosphere, arestricted passage normally connectin said control chamber and the vented portion of saidu per chambr, valve means on said'stem ad i piston for closing said connection when said stem is moved by said piston to force said valveofi its seat, and means for connecting the upper chamber above said piston to the actuator valve of the compressor control system, for connecting the, control chamber valves and for connecting the lower cham r to receive pressure.

--Signed b me at Cleveland, Ohio, this 24th day 0 Au ust, 1923.

' LIAM H. CALLAN.

position and operating through, said stem acent said 

